how to make delete column invisible while editing

while editing no need delete button(whch in gridview last column)
<itemtemplate>
<asp:ImageButton ID="btnDelete" runat="server" ImageUrl="~/Images/delete.jpg" CommandName="delete" ToolTip="Delete"
OnClientClick="return confirm('Are you sure u want to delete this entry');" />
</itemtemplate>

in gv_Rowediting
{
//how to make that delete column invisible..
}